In U.S. Pat. No. 3,836,173 is described an anti-theft device comprising for and aft spurs which are arranged to depend from a towed vehicle when stationary and thrustingly engage the ground if any attempt to move the vehicle is made. The spurs are slidable received in vertically disposed tubular housing members which define openings in the floor of the vehicle. The upper end of each spur is securely held in one of several extended vertical positions by a locking mechanism which is only accessible from the interior of the vehicle. However, this device has the disadvantage that the length of spur which protrudes beneath the vehicle is limited to that achieved in each of the discrete vertical positions wherein the spur can be locked to the housing member. No fine adjustment of the length of the spur is possible and, as a result, the spurs are not suitable for use as stanchions. The device is designed only for use with towed vehicles.
Likewise, GB 2,218,952 describes an anti-theft apparatus wherein an elongate tubular member with a length approximating to the distance between the ground and the floor of the vehicle can be slid downwardly through an annular housing located in the floor of the vehicle and locked into a position wherein a serrated end of the tubular member is in close proximity to the ground. Any attempt to tilt or move the vehicle is then inhibited by the serrated tube end making contact with the ground. However, as the tube can only be locked in one position relative to the annular housing, again no fine adjustment of the position of the tube in the housing can be made to take into account uneven ground.
The object of the present invention is to overcome or substantially mitigate the aforementioned disadvantages.